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Rainfall Forecasting Using Machine Learning Algorithms for Localized Events

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Computers, Materials & Continua 2022年第6期71卷 6333-6350页

作者： Ganapathy Pattukandan Ganapathy Kathiravan Srinivasan Debajit Datta Chuan-Yu Chang Om Purohit Vladislav Zaalishvili Olga Burdzieva centre for Disaster Mitigation and Management Vellore Institute of TechnologyVellore632014India School of Computer Science and Engineering Vellore Institute of TechnologyVellore632014India Department of Computer Science and Information Engineering National Yunlin University of Science and TechnologyYunlin64002Taiwan Service Systems Technology Center Industrial Technology Research InstituteHsinchuTaiwan School of Information Technology and Engineering Vellore Institute of TechnologyVellore632014India geophysical institute of vladikavkaz scientific centre Russian Academy of Sciences(RAS)VladikavkazRussian Federation

A substantial amount of the Indian economy depends solely on ***,on the other hand,plays a significant role in agriculture–while an adequate amount of rainfall can be considered as a blessing,if the amount is inordinate or scant,it can ruin the entire hard work of the *** this work,the rainfall dataset of the Vellore region,of Tamil Nadu,India,in the years 2021 and 2022 is forecasted using several machine learning *** engineering has been performed in this work in order to generate new features that remove all sorts of autocorrelation present in the *** removal of autocorrelation,the data could be used for performing operations on the time-series data,which otherwise could only be performed on any other regular regression *** work uses forecasting techniques like the AutoRegessive Integrated Moving Average(ARIMA)and exponential smoothening,and then the time-series data is further worked on using Long Short Term Memory(LSTM).Later,regression techniques are used by manipulating the *** work is benchmarked with several evaluation metrics on a test dataset,where XGBoost Regression technique outperformed the *** uniqueness of this work is that it forecasts the daily rainfall for the year 2021 and 2022 in Vellore *** work can be extended in the future to predict rainfall over a bigger region based on previously recorded time-series data,which can help the farmers and common people to plan accordingly and take precautionary measures.

关键词： Time-series ARIMA LSTM regression rainfall

Projected Changes in Eurasian and Arctic Summer Cyclones under Global Warming in the Bergen Climate Model

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Atmospheric and Oceanic Science Letters 2009年第1期2卷 62-67页

作者： Yvan J. ORSOLINI Asgeir SORTEBERG Norwegian institute for Air Research geophysical institute University of Bergen Bjerknes centre for Climate Research

Using the coupled ocean-atmosphere Bergen Climate Model,and a Lagrangian vorticity-based cyclone tracking method,the authors investigate current climate summer cyclones in the Northern Hemisphere and their change by the end of the 21st century,with a focus on Northern Eurasia and the *** two scenarios A1B and A2 for increasing greenhouse gas concentrations are *** the model projections,the total number of cyclones in the Northern Hemisphere is reduced by about 3% 4%,but the Arctic Ocean and adjacent coastal re-gions harbour slightly more and slightly stronger summer storms,compared to the model current *** in-crease occurs in conjunction with an increase in the high-latitude zonal winds and in the meridional tempera-ture gradient between the warming land and the ocean across Northern *** in climate model representations of the summer storm tracks at high lati-tudes are also outlined,and the need for further model inter-comparison studies is emphasized.

关键词： Global warming Arctic cyclone climate change

Wintertime Cyclone Activity and Its Relation to Precipitation over China

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Atmospheric and Oceanic Science Letters 2013年第5期6卷 387-393页

作者： CHEN Lei TAN Ben-Kui Nils Gunnar KVAMSTΦ Ola M. JOHANNESSEN Department of Atmospheric and Oceanic Sciences School of Physics Peking University geophysical institute University of Bergen and the Bjerknes Centre for Climate Research Nansen Environmental and Remote Sensing Center Nansen-Zhu International Research centre Institute of Atmospheric Physics Chinese Academy of Sciences Nansen scientific Society

The authors examined the variability in wintertime cyclone activity and storm tracks and their relation to precipitation over China for the period 1951-2006 using the observational *** apparent modes of variability were assumed for the cyclone activity and storm *** first mode describes the oscillation in the strength of the storm tracks in East Asia,which significantly increased since the mid-1980s,whereas the second mode describes a seesaw oscillation in the storm track strength between the Central-Southeast China and northem East *** storm tracks over the Central-Southeast China have increased since the late *** possible causes for the variation of the cyclone activity and storm tracks are also *** is shown that wintertime precipitation,which has increased since the mid-1980s,concentrates in Central-Southeast *** enhancement may be caused by the first mode of variability of storm tracks,whereas the interannual variability of precipitation may be linked to the second mode of the storm track variability.

关键词： cyclones precipitation winter East Asia monsoon

Weak Vertical Diffusion Allows Maintenance of Cold Halocline in the Central Arctic

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Atmospheric and Oceanic Science Letters 2009年第3期2卷 148-152页

作者： Ilker FER geophysical institute University of Bergen & Bjerknes Centre for Climate ResearchBergen Norway

In spring preceding the record minimum summer ice cover detailed microstructure measurements were made from drifting pack ice in the Arctic Ocean, 110 km from the North Pole. Profiles of hydrography, shear, and temperature microstructure collected in the upper water column covering the core of the Atlantic Water are analyzed to determine the diapycnal eddy diffusivity, the eddy diffusivity for heat, and the turbulent flux of heat. Turbulence in the bulk of the cold halocline layer was not strong enough to generate significant buoyancy flux and mixing. Resulting turbulent heat flux across the upper cold halocline was not significantly different than zero. The results show that the low levels of eddy diffusivity in the upper cold halocline lead to small vertical turbulent transport of heat, thereby allowing the maintenance of the cold halocline in the central Arctic.

关键词： Arctic Ocean cold halocline layer turbulence mixing heat flux Atlantic Water

Gas Hydrate Stability Thickness Map along the Margins of India

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地学前缘 2009年第S1期16卷 221-222页

作者： Vayavur Rajesh Kalachand Sain N.Satyavani University centre for Earth & Space Sciences University of Hyderabad National geophysical Research institute

The Gas Hydrate Stability Thickness(GHST)map along the margins of India was prepared from available bathymetry,sea bottom temperature and geothermal *** the Bottom Simulating Reflector(BSR)is often associated with the base of the gas hydrate stability zone,the map helps to identify BSR in case of any doubt for its detection. The map is also useful to the explorer by setting a depth window within which proxies for gas

关键词： bathymetry sea bottom temperature geothermal gradient GHST

Interaction of Waves, Surface Currents, and Turbulence: the Application of Surface-Following Coordinate Systems

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Journal of Ocean University of China 2007年第4期6卷 319-331页

作者： Jenkins Alastair D Bjerknes centre for Climate Research Geophysical Institute Allegaten 70 N-5007 Bergen Norway

Surface waves comprise an important aspect of the interaction between the atmosphere and the ocean, so a dynamically consistent framework for modelling atmosphere-ocean interaction must take account of surface waves, either implicitly or explicitly. In order to calculate the effect of wind forcing on waves and currents, and vice versa, it is necessary to employ a consistent formula- tion of the energy and momentum balance within the airflow, wave field, and water column. It is very advantageous to apply sur- face-following coordinate systems, whereby the steep gradients in mean flow properties near the air-water interface in the cross-interface direction may be resolved over distances which are much smaller than the height of the waves themselves. We may account for the waves explicitly by employing a numerical spectral wave model, and applying a suitable theory of wave–mean flow interaction. If the mean flow is small compared with the wave phase speed, perturbation expansions of the hydrodynamic equations in a Lagrangian or generalized Lagrangian mean framework are useful: for stronger flows, such as for wind blowing over waves, the presence of critical levels where the mean flow velocity is equal to the wave phase speed necessitates the application of more general types of surface-following coordinate system. The interaction of the flow of air and water and associated differences in temperature and the concentration of various substances (such as gas species) gives rise to a complex boundary-layer structure at a wide range of vertical scales, from the sub-millimetre scales of gaseous diffusion, to several tens of metres for the turbulent Ekman layer. The bal- ance of momentum, heat, and mass is also affected significantly by breaking waves, which act to increase the effective area of the surface for mass transfer, and increase turbulent diffusive fluxes via the conversion of wave energy to turbulent kinetic energy.

关键词： wind-wave-current interaction coordinate systems upper-ocean turbulence air-sea exchange of momentum, heat, andmass

The Effect of Diapycnal Mixing on the Ventilation and CFC-11 Uptake in the Southern Ocean

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Advances in Atmospheric Sciences 2004年第5期21卷 755-766页

作者： Helge DRANGE Nansen Environmental and Remote Sensing Center Bergen Norway Nansen-Zhu International Research Centre Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029Bjerknes Centre for Climate Research Bergen Norway Geophysical Institute University of Bergen Bergen Norway

The Miami Isopycnic Coordinate Ocean Model (MICOM) is used to investigate the effect of diapycnal mixing on the oceanic uptake of CFC-11 and the ventilation of the surface waters in the Southern Ocean (south of 45°S). Three model experiments are performed: one with a diapycnal mixing coefficientK d (m2 s?1) of 2 × 10?7/N (Expt. 1), one withK d = 0 (Expt. 2), and one withK d = 5 × 10?8/N (Expt. 3),N (s?1) is the Brunt-V?is?l? frequency. The model simulations indicate that the observed vertical distribution of CFC-11 along 88°W (prime meridian at 0°E) in the Southern Ocean is caused by local ventilation of the surface waters and westward-directed (eastward-directed) isopycnic transport and mixing from deeply ventilated waters in the Weddell Sea region. It is found that at the end of 1997, the simulated net ocean uptake of CFC-11 in Expt. 2 is 25% below that of Expt. 1. The decreased uptake of CFC-11 in the Southern Ocean accounts for 80% of this difference. Furthermore, Expts. 2 and 3 yield far more realistic vertical distributions of the ventilated CFC-waters than Expt. 1. The experiments clearly highlight the sensitivity of the Southern Ocean surface water ventilation to the distribution and thickness of the simulated mixed layer. It is argued that inclusion of CFCs in coupled climate models could be used as a test-bed for evaluating the decadal-scale ocean uptake of heat and CO2.

关键词： chlorofluorocarbons CFC-11 diapycnal mixing ocean modelling ocean ventilation Southern Ocean transient tracers

Drivers of the Severity of the Extreme Hot Summer of 2015 in Western China

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Journal of Meteorological Research 2018年第6期32卷 1002-1010页

作者： Wei CHEN Buwen DONG State Key Laboratory of Numerical Modelling for Atmospheric Sciences and geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences National centre for Atmospheric Science Department of Meteorology University of Reading

Western China experienced an extreme hot summer in 2015,breaking a number of temperature *** summer mean surface air temperature(SAT)anomaly was twice the interannual *** hottest daytime temperature(TXx)and warmest night-time temperature(TNx)were the highest in China since *** extreme hot summer occurred in the context of steadily increasing temperatures in recent *** carried out a set of experiments to evaluate the extent to which the changes in sea surface temperature(SST)/sea ice extent(SIE)and anthropogenic forcing drove the severity of the extreme summer of 2015 in western *** results indicate that about 65%–72% of the observed changes in the seasonal mean SAT and the daily maximumand daily minimum(Tmin)temperatures over western China resulted from changes in boundary forcings,including the SST/SIE and anthropogenic *** the relative role of individual forcing,the direct impact of changes in anthropogenic forcing explain about 42% of the SAT warming and 60%(40%)of the increase in TNxand Tmin(TXxand Tmax)in the model *** changes in SST/SIE contributed to the remaining surface warming and the increase in hot extremes,which are mainly the result of changes in the SST over the Pacific Ocean,where a super El Ni?o event *** study indicates a prominent role for the direct impact of anthropogenic forcing in the severity of the extreme hot summer in western China in 2015,although the changes in SST/SIE,as well as the internal variability of the atmosphere,also made a contribution.

关键词： severity of temperature extremes summer 2015 western China anthropogenic forcing

Interdecadal Enhancement of the Walker Circulation over the Tropical Pacific in the Late 1990s

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Advances in Atmospheric Sciences 2013年第2期30卷 247-262页

作者： Buwen DONG 陆日宇 National centre for Atmospheric Science-Climate Department of MeteorologyUniversity of Reading State Key Laboratory of Numerical Modelling for Atmospheric Sciences and geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences

The Walker circulation is one of the major components of the large-scale tropical atmospheric circulation and variations in its strength are critical to equatorial Pacific Ocean circulation. It has been argued in the literature that during the 20th century the Walker circulation weakened, and that this weakening was attributable to anthropogenic climate change. By using updated observations, we show that there has been a rapid interdecadal enhancement of the Walker circulation since the late 1990s. Associated with this enhancement is enhanced precipitation in the tropical western Pacific, anomalous westerlies in the upper troposphere, descent in the central and eastern tropical Pacific, and anomalous surface easterlies in the western and central tropical Pacific. The characteristics of associated oceanic changes are a strengthened thermocline slope and an enhanced zonal SST gradient across the tropical Pacific. Many characteristics of these changes are similar to those associated with the mid-1970s climate shift with an opposite sign. We also show that the interdecadal variability of the Walker circulation in the tropical Pacific is inversely correlated to the interdecadal variability of the zonal circulation in the tropical Atlantic. An enhancement of the Walker circulation in the tropical Pacific is associated with a weakening zonal circulation in the tropical Atlantic and vise versa, implying an inter-Atlantic-Pacific connection of the zonal overturning circulation variation. Whether these recent changes will be sustained is not yet clear, but our research highlights the importance of understanding the interdecadal variability, as well as the long-term trends, that influence tropical circulation.

关键词： Walker circulation interdecadal change Interdecadal Pacific Oscillation late 1990s